Reducing the deterioraton of wetted hydrophilic coatings comprising water subjected to sterilization by radiation

ABSTRACT

A method of reducing the deterioration of a wetted hydrophilic coating comprising water at the time of sterilization by radiation is provided. The method comprises the step of reducing the amount of oxygen in an atmosphere in contact with the wetted hydrophilic coating in addition to any reduction in oxygen provided by oxygen scavengers that may be present in the wetted hydrophilic coating.

FIELD

The field of the invention is the sterilization and stabilization of wetted hydrophilic coatings.

BACKGROUND

Many medical devices, such as guide wires, intermittent and (cardio)vascular catheters or other medical tubing, syringes, and membranes require some sort of lubrication in order to facilitate insertion into or removal from the body. Pain or soft tissue damage can occur upon insertion or removal of the medical device if the medical device is not properly lubricated.

Many medical devices are coated with a hydrophilic coating that must be wetted with a liquid to attain the sufficient level of lubrication. A hydrophilic coating is typically provided as a coating on a surface of a medical device. The act of wetting a hydrophilic coating is performed by causing the hydrophilic coating to retain a wetting agent. Upon being wetted with a wetting agent, a hydrophilic coating may absorb at least two times its weight of the wetting agent and be rendered lubricious. A hydrophilic coating that does not absorb at least two times its weight of wetting agent will likely be insufficiently lubricous. The wetting agent may be any number of water or oil-based products, for example those disclosed in WO2006037321, assigned to Coloplast A/S, or WO2013017547, assigned to DSM IP Assets B.V.

Water-based wetting agents are often preferred by users. Unlike oil-based wetting agents, such as those that contain more than 50% by weight of propylene glycol or glycerol, water-based wetting agents do not have the disadvantage of leaving an oily residue on surfaces that come in contact with the wetted hydrophilic coating, such as a user's fingers. Furthermore, although a hydrophilic coating that is wetted with an oil-based wetting agent generally has good lubricious properties and dry-out time, improved lubricity can often be realized when a hydrophilic coating is wetted with a water-based wetting agent. Dry-out time is the amount of time that the wetted hydrophilic coating can retain suitable lubricious properties.

A hydrophilic coating may be wetted in a number of ways, depending on the composition of the wetting agent and the medical device design. For example, the hydrophilic coating may be wetted by submersing the hydrophilic coating in the wetting agent, spraying the wetting agent on the hydrophilic coating, running wetting agent over the hydrophilic coating for a short period of time, injecting the wetting agent into a packaging containing an article comprising a hydrophilic coating, or applying the wetting agent to the hydrophilic coating in the form of a gas, for instance in a high humidity environment.

The hydrophilic coating may be wetted immediately prior to use. Wetting immediately prior to use requires access to a wetting agent, for instance, a water source. Moreover, wetting immediately prior to use requires handling of the medical device at the risk of contacting the medical device with bacteria.

Because of the disadvantages with wetting the hydrophilic coating on a medical device immediately prior to use, numerous medical devices have been introduced that are sterile, pre-wetted, and individually packaged for immediate use. The use of so-called “ready-to-use” products may reduce the risk of contact with bacteria, and allows for the medical device to be used when access to a wetting agent is not practical or possible. A ready-to-use product typically comprises a wetted hydrophilic coating wherein the wetted hydrophilic coating comprises at least 70 wt %, or more preferably at least 90 wt % of wetting agent, based on the total weight of the wetted hydrophilic coating (i.e. the combined weight of the wetting agent and the hydrophilic coating). A product that does not possess a wetted hydrophilic coating that is sufficiently lubricious is not a ready-to-use product. An example of a ready-to-use product is described in U.S. Pat. No. 7,380,658, hereby incorporated by reference in its entirety.

In addition to numerous benefits, ready-to-use products present numerous challenges. One challenge faced is to avoid a reduction in the lubricious properties, durability, or dry-out time of the hydrophilic coating as a result of sterilization. Certain sterilization techniques, such as sterilization with radiation, are known to potentially degrade the beneficial properties of a wetted hydrophilic coating. Consequently, various attempts have been made to reduce the damaging effects of sterilization on the beneficial properties of a hydrophilic coating wetted with a wetting agent comprising water prior to sterilization.

For example, a known technique described in WO/2000/030696, assigned to Coloplast A/S, involves wetting a hydrophilic coating on a medical device with an aqueous wetting agent comprising a hydrophilic polymer prior to sterilizing the medical device. However, the presence of polymers in the water phase can leave sticky residues on fingers and clothes. Moreover, an insufficiently cross-linked additional coating layer may be formed that is not acceptably durable.

Another known technique described in WO/2007/137699, assigned to DSM IP Assets B.V., involves the use of a compound selected from the group consisting of aliphatic compounds, alicyclic compounds and antioxidants for protecting a hydrophilic coating wetted with water. This technique may provide insufficient protection from the damaging effects of radiation at certain doses of radiation, such as greater than 30 kGy.

Therefore, an improved way of protecting a hydrophilic coating wetted with a wetting agent comprising water prior to sterilization from the damaging effects of radiation is desired.

SUMMARY

Without wishing to be bound by any theory, the inventors suspect that the damage caused by radiation sterilization of wetted hydrophilic coatings comprising water results from the presence of oxygen. Radicals formed in the wetted hydrophilic coating by the radiation combine with oxygen to deteriorate the wetted hydrophilic coating. Oxygen is present in the wetted hydrophilic coating comprising water itself, and in an atmosphere in contact with the wetted hydrophilic coating. The inventors have discovered that the effects of oxygen in the atmosphere in contact with the wetted hydrophilic coating cannot be ignored.

In accordance with the invention, the deterioration of a wetted hydrophilic coating comprising water at the time of sterilization by radiation is reduced by reducing the amount of oxygen in an atmosphere in contact with the wetted hydrophilic coating in addition to any reduction in oxygen provided by oxygen scavengers that may be present in the wetted hydrophilic coating, wherein the wetted hydrophilic coating comprises at least 70 wt %, or more preferably at least 90 wt % water, based on the total weight of the wetted hydrophilic coating. As opposed to the prior art, which sought to avoid the damaging effects of sterilization solely by addressing the content of the wetted hydrophilic coating, the inventors have discovered that the oxygen in the atmosphere contacting the wetted hydrophilic coating may be controlled to reduce the damaging effects of radiation sterilization.

Further embodiments of the invention relate to a method of sterilizing a packaged article comprising the step of sterilizing with radiation a package comprising an article and a gas impermeable packaging enclosing the article, the article comprising a wetted hydrophilic coating, the wetted hydrophilic coating comprising water, and the package comprising an amount of oxygen that is less than an amount of oxygen that would have been present in the package if oxygen scavengers that may be present in the wetted hydrophilic coating were alone acting on ambient air at the time of packaging within the gas impermeable packaging, wherein the wetted hydrophilic coating comprises at least 70 wt %, or more preferably at least 90 wt % water, based on the total weight of the wetted hydrophilic coating.

A further embodiment of the invention relates to a method of packaging an article comprising the steps of providing an article comprising a hydrophilic coating; wetting the hydrophilic coating with a wetting agent comprising water, thereby forming a wetted hydrophilic coating; reducing the amount of oxygen in an atmosphere in contact with the wetted hydrophilic coating in addition to any reduction in oxygen provided by oxygen scavengers that may be present in the wetted hydrophilic coating; and enclosing the article in a gas impermeable packaging, wherein the wetted hydrophilic coating comprises at least 70 wt %, or more preferably at least 90 wt % water, based on the total weight of the wetted hydrophilic coating.

Another embodiment of the invention is a package comprising an article comprising a wetted hydrophilic coating, the wetted hydrophilic coating comprising water; a gas impermeable packaging enclosing the article, and an atmosphere within the gas impermeable packaging and in contact with the wetted hydrophilic coating that has an amount of oxygen that is less than an amount of oxygen that would have been present if oxygen scavengers that may be present in the wetted hydrophilic coating were alone acting on ambient air at the time of packaging within the gas impermeable packaging, wherein the wetted hydrophilic coating comprises at least 70 wt %, or more preferably at least 90 wt % water, based on the total weight of the wetted hydrophilic coating.

In such embodiments, the article is preferably a medical device, such as a catheter, guidewire, syringe, or contact lens.

Further embodiments of the invention are elucidated in the following detailed description.

DETAILED DESCRIPTION

As mentioned above, the prior art of reducing the deterioration of wetted hydrophilic coatings subject to sterilization by radiation has failed to suitably address the role that oxygen in the atmosphere in contact with the wetted hydrophilic coating plays in coating deterioration when the wetted hydrophilic coating comprises substantial amounts of water.

The prior art has recognized some reduction in deterioration may occur from employing components that may have oxygen and radical scavenging capabilities in the wetted hydrophilic coating, but a sufficient level of deterioration reduction was not obtained. For example, WO/2007/137699 mentions Vitamin C, which may act as both an oxygen scavenger and a radical scavenger. However, WO/2007/137699 notes that when a hydrophilic coating wetted with a wetting agent consisting essentially of water and Vitamin C is sterilized with 25 kGy of gamma radiation, as shown in Examples B and C of WO/2007/137699, “some improvement was observed compared to sterilization in pure water, but . . . a desirable dry-out time was not realized.” Additionally, the improvement exhibited with a wetting agent consisting essentially of water and 2 wt % vitamin C exhibited coloration after sterilization.

The inventors now theorize that the oxygen and/or radical scavenging abilities of the vitamin C are exhausted prior to sterilization. By reducing the amount of oxygen in an atmosphere in contact with the wetted hydrophilic coating beyond the reduction in oxygen that would otherwise be provided by any oxygen scavengers that may be present in the wetted hydrophilic coating, the oxygen scavenger and radical scavenger are able to perform their functions sufficiently prior, during, and after sterilization. Additionally, potentially less oxygen scavenger and/or radical scavenger are needed in the wetted hydrophilic coating, thereby allowing for components, such as additional water, that perform the sole function of providing lubricity to the wetted hydrophilic coating or have a lower raw material cost.

In accordance with the invention, the deterioration of a wetted hydrophilic coating comprising water at the time of sterilization by radiation is reduced by reducing the amount of oxygen in an atmosphere in contact with the wetted hydrophilic coating in addition to any reduction in oxygen provided by oxygen scavengers that may be present in the wetted hydrophilic coating, wherein the wetted hydrophilic coating comprises at least 70 wt %, or more preferably at least 90 wt % water, based on the total weight of the wetted hydrophilic coating.

A hydrophilic coating is typically provided on a surface of an article. A hydrophilic coating may be provided in a number of ways, such as extrusion, molding, or curing. In the case of curing, a hydrophilic coating composition is cured to form a hydrophilic coating. A hydrophilic coating composition is typically present as a liquid, but may also be present as a paste or some other form. Radiation curing may be performed by curing with heat and/or light, such as UV light. Preferably, the hydrophilic coating is formed by curing a hydrophilic coating composition by radiation comprising UV light.

A typical hydrophilic coating may be obtained by providing on a surface of an article, said surface may or may not being already primed by a primer, a hydrophilic coating composition and curing the hydrophilic coating composition. A typical hydrophilic coating composition comprises a hydrophilic polymer, a solvent, and an initiator. Examples of hydrophilic polymers are polyvinylpyrrolidone (PVP), polyacrylamide, polyelectrolytes, and poly(ethylene oxide). Hydrophilic polymers may also comprise reactive groups, such as (meth)acrylate groups) or photo-active groups, in addition to a hydrophilic portion. The reactive groups contribute to the formation of a polymer network when the hydrophilic coating composition is cured to form a hydrophilic coating. The initiator is typically a photoinitiator. One or more supporting monomers, oligomers, or polymers having reactive moieties to support the hydrophilic polymer or other components or additives, such as plasticizers or surfactants, may also be present. A solvent may be, for example, water, methanol or ethanol. The hydrophilic coating may be obtained by at least partially evaporating the solvent from the hydrophilic coating composition and then curing the hydrophilic coating composition with light, such as UV light. Hydrophilic coating compositions are disclosed in, for example, US2011046255 to DSM IP Assets BV, which is hereby incorporated by reference in its entirety. A commercial example of a hydrophilic coating composition that may be cured by radiation comprising UV light to form a hydrophilic coating is a ComfortCoat® product from DSM, such as TC43005.

A primer may be present to improve the adherence of the hydrophilic coating to an article. The primer may be cured prior to application and curing of a hydrophilic coating composition, or may be cured at the same time as the hydrophilic coating composition is cured.

A typical primer composition may comprise a supporting monomer, oligomer, or polymer that provides the necessary adherence to the article, an initiator, and a solvent. The initiator is typically a photoinitiator. A hydrophilic polymer, such as polyvinylpyrrolidone (PVP) and poly(ethylene oxide), may also be present. The primer may be formed by at least partially evaporating the solvent from the primer composition and then curing the primer composition with UV light. Subsequently, a hydrophilic coating composition may be applied on top of the primer and cured to form a hydrophilic coating.

In an embodiment, a hydrophilic coating is formed by curing a hydrophilic coating composition, the hydrophilic coating composition comprising at least 70 wt %, preferably at least 80 wt %, more preferably at least 90 wt % of hydrophilic polymers, based on the total dry weight of the hydrophilic coating composition. By dry weight it is meant the total weight of the hydrophilic coating composition excluding any solvents.

A wetted hydrophilic coating may be formed in a number of ways. The process of forming a wetted hydrophilic coating from a hydrophilic coating is known as wetting the hydrophilic coating. Wetting can be accomplished by, for example, bringing a wetting agent present as a liquid into contact with a hydrophilic coating. The contact may be established in a number of ways, for instance, submerging the hydrophilic coating in the wetting agent or spraying the hydrophilic coating with the wetting agent. Other methods of wetting a hydrophilic coating may be performed with a wetting agent present as a gas or vapor. For instance, a liquid wetting agent may be present out of direct contact with the hydrophilic coating, but the wetting agent wets the hydrophilic coating by traveling as a gas or vapor. Similarly, a high humidity environment could be present in a package containing an article comprising a hydrophilic coating such that over time the hydrophilic coating is wetted. In a wetting method where the wetting agent wets the hydrophilic coating as a gas or vapor, components that may normally be included in the wetting agent that cannot travel as a vapor or gas would need to be incorporated into the wetted hydrophilic coating by other means, such as inclusion in the hydrophilic coating itself. The thickness of a typical wetted hydrophilic coating is generally more than 0.5 micron and less than 100 microns.

Sterilization is typically performed by radiation. Methods of sterilization by radiation include sterilization by gamma rays, x-rays, and electron beams. In the medical device area, gamma ray or electron beam sterilization are generally preferred. In an embodiment, sterilization is performed by gamma rays or electron beam. In an embodiment, sterilization is performed by gamma rays or electron beam at a dosage of greater than 25 kGy, preferably greater than 30 kGy. Catheters are typically sterilized with a dose of radiation of from 25 to 50 kGy, preferably 25 to 45 kGy.

Generally, chemical or other means of sterilization present difficulties when sterilizing wetted hydrophilic coatings. Chemical sterilization, such as sterilization with ethylene oxide, requires the use of a gas that must contact the article that is being sterilized. A vacuum is then applied to remove the gas. This vacuum may adversely affect the wetted hydrophilic coating by removing some of the liquid components of a wetting agent retained by the wetted hydrophilic coating, thereby reducing the lubricity of the wetted hydrophilic coating. Moreover, depending on the type of packaging used, a chemical sterilization may not fully penetrate a sealed package and consequently not sufficiently sterilize the article.

In accordance with the invention, the wetted hydrophilic coating comprises water. In embodiments, the wetted hydrophilic coating comprises at least 70 wt %, more preferably at least 90 wt % water, based on the total weight of the wetted hydrophilic coating. In embodiments wherein the wetted hydrophilic coating is wetted with a wetting agent comprising water, the amount of water in the wetting agent may be at least 70 wt %, more preferably at least 90 wt %, based on the total weight of the wetting agent. In an embodiment, a wetting agent comprises at least 95 wt % water.

In embodiments of the invention, a radical scavenger is incorporated in the wetted hydrophilic coating. In principle any known radical scavenger that is soluble in water could be used. In the case that the wetted hydrophilic coating will be inserted into the body, for instance in the case of a catheter, the radical scavenger should be biocompatible. Biocompatible means that a material has the ability to be in contact with a living system without producing an adverse effect. In an embodiment where a radical scavenger is present in a wetted hydrophilic coating, the total concentration of radical scavenger in the wetting hydrophilic coating is preferably from 0.01 to 2 wt %, based on the total weight of wetted hydrophilic coating. In the case that a radical scavenger is present in a wetting agent for wetting a hydrophilic coating, the total concentration of radical scavenger in the wetting agent is preferably from 0.01 to 2 wt %, based on the total weight of wetting agent.

In an embodiment, a wetted hydrophilic coating and/or a wetting agent comprises a radical scavenger and an oxygen scavenger. Preferably, the radical scavenger is also an oxygen scavenger. Preferably, the radical scavenger and oxygen scavenger is vitamin c (ascorbic acid) or a compound comprising a thiosulfate anion. Compounds comprising thiosulfate anions are, for example, sodium thiosulfate, ammonium thiosulfate, barium thiosulfate, calcium thiosulfate, magnesium thiosulfate, potassium thiosulfate or hydrates thereof. Additional compounds comprising a thiosulfate anion are lithium thiosulfate, iron thiosulfate, zinc thiosulfate, tin thiosulfate, silver thiosulfate or hydrates thereof. In the case that the wetted hydrophilic coating or wetting agent comprises a thiosulfate anion, it is preferred that the wetted hydrophilic coating or wetting agent is maintained at a pH of 6 or higher, more preferably 7 or higher. In an embodiment, a buffer is present for maintaining the pH at 6 or higher, preferably 6.5 or higher, and more preferably 7 or higher. In the case that the radical scavenger is also an oxygen scavenger and is present in a wetting agent for wetting a hydrophilic coating, the total concentration of radical scavenger that is also an oxygen scavenger in the wetting agent is from 0.05 to 2 wt % based on the total weight of wetting agent, more preferably 0.3 to 1.5 wt % based on the total weight of wetting agent. In an embodiment, the total concentration of radical scavenger that is also an oxygen scavenger in the wetting agent is from 0.5 to 1.5 wt % based on the total weight of wetting agent.

Suitable compounds that are radical scavengers but not oxygen scavengers are, for example, alkyl hydroxybenzyl alcohols (such as 5-di-tert-butyl-4-hydroxybenzyl alcohol), alkyl hydroxybenzoic acids (such as 3,5-di-tert-butyl-4-hydroxybenzoic acid), pyrogallol, alkylated hydroxytoluene (such as butylated hydroxy toluene), and 2,6-ditertbutyl-4-ethyl-phenol. Commercially available examples of such radical scavengers that are not oxygen scavengers include Irganox® 1300, Irganox® 1098, Irganox® 1076 and combinations thereof. If present, a compound that is a radical scavenger but not an oxygen scavenger may be present in an amount of from 0.05 to 1 wt %, based on the total weight of wetting agent.

The radical scavenger may be incorporated into the wetted hydrophilic coating in a number of ways. For example, the radical scavenger may be present as a wetting agent that is used to wet the hydrophilic coating, may be present in the hydrophilic coating itself, or in both. If present in the wetting agent, the radical scavenger may be incorporated in the wetting agent by simple mixing. If present in the hydrophilic coating, the radical scavenger may be incorporated in the hydrophilic coating composition.

Further oxygen scavengers may be present in the wetted hydrophilic coating provided that they are biocompatible.

In an embodiment, a further water soluble organic component and/or water soluble polymer is incorporated into the wetted hydrophilic coating or present in a wetting agent. Such components may be, for example, polyvinylpyrrolidone, acrylic acid or acrylic acid copolymers, polyacrylamides, polyethylene glycol, and/or polyelectrolytes such as salts of (meth)acrylic acid copolymers, for example, poly(acrylamide-co-acrylic acid) salt.

Further alcohols may be present in the wetted hydrophilic coating and/or wetting agent in limited amounts. In an embodiment, the wetted hydrophilic coating and/or wetting agent comprises a component selected from the group consisting of glycerol, glycerol esters, glycerol ethers, glycols, glycolesters and glycolethers. Suitable examples of components are glycerol, monoacetin, diacetin, diacetone alcohol, diethyleneglycol, triethyleneglycol, tetraethyleneglycol, propyleneglycol or dipropyleneglycol. If present, it is preferred that such components are present at from 1 wt % to 20 wt %, more preferably from 2 wt % to 10 wt %, more preferably from 4 wt % to 10 wt %, based on the total weight of the wetting agent.

In embodiments of the invention, further components that may be present in the wetted hydrophilic coating and/or wetting agent are preservatives, surfactants, buffers, antibiotics, and/or anti-microbial compounds. Examples of preservatives are methyl paraben, ethyl paraben, propyl paraben, salts of sulfite such as sodium sulfite, sorbic acid, calcium propionate, benzoic acid, salts of hydrosulfite such as sodium hydrogen sulfite, sodium bisulfite, sodium benzoate, erythorbic acid, and salts of nitrate such as potassium nitrate. In the case that the a buffer is present, for instance to stabilize the pH of the wetting agent, the buffer keeps the pH above 4, preferably above 6, more preferably from 6.5 to 8, and more preferably about 7.

In accordance with the invention, the amount of oxygen in an atmosphere in contact with the wetted hydrophilic coating is reduced in addition to any reduction in oxygen provided by oxygen scavengers that may be present in the wetted hydrophilic coating. The atmosphere in contact with the wetted hydrophilic coating means the gas surrounding and in contact with the wetted hydrophilic coating at the time of sterilization. For example, the atmosphere may be contained within a gas impermeable package or within a sterilization apparatus.

An oxygen scavenger present in the wetted hydrophilic coating will, depending on type and amount, generally provide some reduction in the oxygen in the atmosphere in contact with the wetted hydrophilic coating. As mentioned above, an oxygen scavenger may also be a radical scavenger, for example vitamin C. However, deterioration of the wetted hydrophilic coating may be improved by a reduction in the amount of oxygen in an atmosphere in contact with the wetted hydrophilic coating in addition to any reduction in oxygen provided by oxygen scavengers that may be present in the wetted hydrophilic coating. In an embodiment, the amount of oxygen in the atmosphere in contact with the wetted hydrophilic coating is reduced below 15%, more preferably below 10%, and even more preferably below 5% by volume of the atmosphere in contact with the wetted hydrophilic coating.

For present commercial purposes, wetted hydrophilic coatings that are sterilized are preferably present on articles packaged in a gas impermeable packaging. These individually packaged articles are typically medical devices, such as catheters. However, it is possible that the articles are not individually packaged. In such a case, the oxygen in the atmosphere can be reduced by wholly or partially substituting the oxygen in the sterilization chamber with another gas, such as nitrogen, carbon dioxide, argon or another non-reactive gas.

In an embodiment, the oxygen in the atmosphere is reduced by replacing some of the atmosphere in contact with the wetted hydrophilic coating with an alternative gas, such as nitrogen, carbon dioxide, argon or another non-reactive gas. The atmosphere replacement may be performed by simply inserting the alternative gas into a gas impermeable package prior to sealing the gas impermeable package. Inserting the alternative gas at a pressure above atmospheric pressure is desirable, but care should be taken not to insert the alternative gas at too high of pressure or the wetted hydrophilic coating may be affected. For example, some of the wetting agent that has wetted the hydrophilic coating may be inadvertently removed by the high pressure insertion of an alternative gas. Similarly, removal of the oxygen in the atmosphere by a vacuum is also possible, but care should be taken to operate the vacuum to not inadvertently affect the wetted hydrophilic coating detrimentally. Of course, some gasses other than oxygen may be removed when inserting an alternative gas or using a vacuum, for instance if the original atmosphere is air, but reducing the amount of oxygen in an atmosphere in contact with the wetted hydrophilic coating is achieved if the amount of oxygen is less than prior to carrying out the step.

In an embodiment, the oxygen in the atmosphere is reduced by incorporating an oxygen scavenging packaging component. An oxygen scavenging packaging component may be an item inside a gas impermeable packaging or part of the gas impermeable packaging itself.

Accordingly, in a further embodiment, an oxygen scavenging packaging component is included in the form of an oxygen scavenging packet. For example, the oxygen scavenging packet may be a gas-permeable package containing an oxygen scavenger. The oxygen scavenging packet may be secured or otherwise included inside a gas impermeable packaging. Preferably, such an oxygen scavenging packet is held out of contact with the wetted hydrophilic coating.

The use of such oxygen scavenging packets allows for oxygen scavengers contained within the packet that are not necessarily biocompatible or dissolvable in a wetted hydrophilic coating. For example, the oxygen scavenger in the oxygen scavenging packet may be iron powder, zinc powder, manganese powder, vitamin C, or sodium thiosulfate. Commercial examples of oxygen scavenging packets that are satchets containing an oxygen scavenger are Ageless from Mitsubisihi Gas and Chemical Co., Japan, ATCO products from Emco Packaging Systems, UK, and Standa Industries, France, Freshilizers series from Toppan Printing, Japan, FreshPax® and FreshMax® from Multisorb Technologies, Inc. USA, Bioka oxygen absorbing satchets from Bioka Ltd. Finland, and Oxyguard from Toyo Seikan Kaisha, Japan. In an embodiment, the oxygen scavenging packet is water-activated.

In an embodiment, the oxygen scavenging packaging component is an oxygen scavenging surface. Such oxygen scavenging surfaces are known from, for example U.S. Pat. No. 6,406,766 and U.S. Pat. No. 6,346,308, assigned to BP Corporation of North America, and US20080206500, assigned to DSM IP Assets BV, each hereby incorporated by reference in its entirety. Such an oxygen scavenging surface may be formed from a co-extruded plastic. Oxygen scavenging surfaces are available commercially, for example as Cryovac® OS Films—Active Barrier Films.

Such an oxygen scavenging surface may be present as an internal surface of an outer packaging or as a separate packaging component within an outer packaging. In an embodiment, the oxygen scavenging packaging component is a sleeve comprising an oxygen scavenging surface that is placed around an article inside an outer packaging. Such a sleeve may have the added benefit of providing a surface with which the article may be handled without touching a surface of the article immediately prior to use. In an embodiment, the sleeve is gas impermeable.

In an embodiment of the invention, a method of sterilizing a packaged article is provided comprising the step of sterilizing with radiation a package comprising an article and a gas impermeable packaging enclosing the article, the article comprising a wetted hydrophilic coating, the wetted hydrophilic coating comprising water, and the package comprising an amount of oxygen that is less than an amount of oxygen that would have been present in the package if oxygen scavengers that may be present in the wetted hydrophilic coating were alone acting on ambient air at the time of packaging within the gas impermeable packaging, wherein the wetted hydrophilic coating comprises at least 70 wt %, or more preferably at least 90 wt % water, based on the total weight of the wetted hydrophilic coating.

By ambient air at the time of packaging it is meant the composition of the surrounding gasses present at the time of packaging that contain a sufficient amount of oxygen for a human to function normally for an extended period of time without the aid of a breathing apparatus. Ambient air at the time of packaging generally has a percentage of oxygen that is similar to the atmosphere of earth (approximately 20.9% oxygen) at a pressure of 1 atm and may be controlled in some way. For example, ambient air at the time of packaging may be controlled by controlling the temperature and/or humidity of the ambient air at the time of packaging. The situation of packaging an article in an environment comprising an amount of oxygen that is not a sufficient amount of oxygen for a human to function normally for an extended period of time without the aid of a breathing apparatus would not be considered packaging in ambient air, but would rather be a step of reducing the amount of oxygen in an atmosphere in contact with the wetted hydrophilic coating in addition to any reduction in oxygen provided by oxygen scavengers that may be present in the wetted hydrophilic coating.

A further embodiment of the invention is a method of packaging an article comprising the steps of providing an article comprising a hydrophilic coating; wetting the hydrophilic coating with a wetting agent comprising water, thereby forming a wetted hydrophilic coating, wherein the wetted hydrophilic coating comprises at least 70 wt %, or more preferably at least 90 wt % water, based on the total weight of the wetted hydrophilic coating; reducing the amount of oxygen in an atmosphere in contact with the wetted hydrophilic coating in addition to any reduction in oxygen provided by oxygen scavengers that may be present in the wetted hydrophilic coating; and enclosing the article in a gas impermeable packaging.

An article may be enclosed in a gas impermeable packaging by any number of common methods. For example, the article may be enclosed in gas impermeable packaging by sealing the gas impermeable packaging. For example, the sealing may be carried out by activating an adhesive. Sealing could also be performed by bonding together two surfaces of a gas impermeable packaging with the aid of heat and/or pressure.

Another embodiment of the invention is a package comprising an article comprising a wetted hydrophilic coating, the wetted hydrophilic coating comprising water, wherein the wetted hydrophilic coating comprises at least 70 wt %, or more preferably at least 90 wt % water, based on the total weight of the wetted hydrophilic coating, a gas impermeable packaging enclosing the article, and an atmosphere within the gas impermeable packaging and in contact with the wetted hydrophilic coating that has an amount of oxygen that is less than an amount of oxygen that would have been present if oxygen scavengers that may be present in the wetted hydrophilic coating were alone acting on ambient air at the time of packaging within the gas impermeable packaging.

In an embodiment, a method of reducing the deterioration of a wetted hydrophilic coating comprising water at the time of sterilization by radiation is provided, the method comprising the step of reducing the amount of oxygen in an atmosphere in contact with the wetted hydrophilic coating to an amount that is less than an amount of oxygen that would have been present after exhausting all oxygen scavengers that may be present in the wetted hydrophilic coating, wherein the wetted hydrophilic coating comprises at least 70 wt %, or more preferably at least 90 wt % water, based on the total weight of the wetted hydrophilic coating.

The following examples are used to further illustrate the invention, but, of course, should not be construed as in any way limiting its scope.

Examples

Hydrophilic coatings are provided on pieces of 14Fr (external diameter of 4.667 mm) PVC tubing with a length of 40 cm. The tubing is useful for intermittent catheter products.

Coating and Curing Process

The primer composition was P41001, a primer composition available from DSM Biomedical, Inc. P41001 comprises a hydrophilic polymer comprising reactive groups, a further hydrophilic polymer, a photoinitiator and greater than 90 wt % of solvent, based on the total weight of the primer composition. The hydrophilic coating composition was TC43005, a UV-curable hydrophilic coating composition available from DSM Biomedical, Inc. TC43005 comprises a hydrophilic polymer, a polyelectrolyte hydrophilic polymer, a photoinitiator, and greater than 90 wt % of solvent, based on the total weight of the hydrophilic coating composition.

A metal mandrel was inserted into the end of a piece of PVC tubing and subsequently attached into the device holder of a Harland PCX coater. The dip length for the primer composition was 35 cm. The dip length for the hydrophilic coating composition was 34 cm.

Pieces of PVC tubing were dip coated and cured using the Harland PCX coater. Extraction speed of the coated tubing was 1 cm/s for both the primer and hydrophilic coating formation. Cure took place directly after application of the hydrophilic coating composition. Intensity of the lamps was on average 60 mW/cm2 and was measured using a Harland UVR 335 (also known as IL 1400), equipped with an International Light detector SED 005#989. Input optic: W#11521, filter wbs320#27794. The instruction manual of International Light was applied, which is available on the internet: www.intl-light.com. UV dose was approximately 0.9 J/cm2 for the primer and 21.6 J/cm2 for the hydrophilic coating. The primer composition was coated and cured first, and then the hydrophilic coating composition was coated and cured. After curing, a coated tubing comprising a hydrophilic coating was obtained.

Preparation of a Wetted Hydrophilic Coating

A wetting agent is formed by weighing the components of the wetting agent and simply mixing together the components in a glass bottle. The compositions of the wetting agents are shown in the below Table 3 in weight percent, based on the total amount of wetting agent. The water was demineralized water. Shortly after preparing the wetting agent, the hydrophilic coatings on the pieces of coated tubing formed above are wetted by immersion for one minute in the wetting agent, thereby forming pieces of coated tubing comprising a wetted hydrophilic coating.

Packaging

A gas impermeable, heat sealable packaging with an external surface of an aluminum foil and an internal surface of polyethylene foil were obtained from Steripack (U/P Pouch 70*505 mm SO5198). 2.5 ml of wetting agent was inserted into each gas impermeable packaging prior to placing the coated tubing comprising a wetted hydrophilic coating in the gas impermeable packaging. Each piece of coated tubing comprising a wetted hydrophilic coating was then individually placed in a gas impermeable package and the package was sealed by applying heat, thereby forming a package.

Atmosphere Replacement

In the case that the specific package was subject to an atmosphere replacement before sealing of the package, the atmosphere replacement was performed by injecting argon at a pressure of 0.5 bar. After approximately 30 seconds, the package was sealed such that a significant quantity of argon was contained within the package.

Sterilization

The packages were sterilized by exposing them to 45 kGy of γ-radiation.

Lubricity and Durability

After sterilization, the pieces of coated tubing comprising a wetted hydrophilic coating are tested for lubricity and durability. The sterilized package was opened shortly before testing. The tests were performed using a Harland FTS5000 Friction Tester (HFT). The lubricity and durability measurements are performed in water. The protocol was as indicated in the following table:

TABLE 1 HFT settings transport movement (cm) 10 clamp force (g) 300 pull speed (cm/s) 1 acceleration time (sec) 2 number of rubs 25

Friction tester pads from Harland Medical Systems were used: P/N 102692, FTS5000 Friction Tester Pads, 0.125″0.5″0.125″60 durometer. A metal mandrel was inserted into a piece of coated tubing comprising a wetted hydrophilic coating and the test started.

The lubricity of the wetted hydrophilic coating is defined as the friction force measured after the first cycle. A friction force of less than 15 gram is considered to be very good. The durability of the wetted hydrophilic coating is defined as the difference between the friction force measured after the 25^(th) cycle and the friction force measured after the first cycle. The durability is a measure of the adhesion of the wetted hydrophilic coating on a surface and coating integrity. A durability of less than 5 grams is considered to be very good.

A typical lubricity value for unsterilized coated tubing with a wetted hydrophilic coating wetted with 100% water is 5-10 grams. A typical value for durability of such unsterilized coated tubing is less than 5 gram.

Characterization of Deterioration

Deterioration is characterized by loss of lubricity and durability in the friction tester. The amount of deterioration is also assessed by comparison to the lubricity of an unsterilized wetted hydrophilic coating with 100 wt % water as the wetting agent by gentle rubbing of the wetted coated tubing between the pointer finger and the thumb immediately after removal from the sterilized package. Deterioration of the wetted hydrophilic coating was assessed using the criteria in table 2, below.

TABLE 2 Deterioration Level Description 0 No deterioration observed 1 Deterioration is observed, but the lubricity is not significantly affected. Thinning of the wetted hydrophilic coating is observed. 2 Deterioration is observed and the lubricity of the wetted hydrophilic coating is somewhat adversely affected. 3 Significant improvement over a wetting agent comprising 100 wt % of water, but significant deterioration is still observed. 4 Very little improvement over a wetting agent comprising 100 wt % of water, significant deterioration is observed. 5 Baseline level of deterioration for the case when the wetting agent comprises 100 wt % water.

The pre-sterilization lubricity of each sample was about 5 to 10 g. Results of the experiment are reported in Table 3 below.

TABLE 3 Deterio- Atmosphere Lubricity Durability ration Ex. Wetting agent replacement (g) (g) level 1 100 wt % water no >>100 >50 gr after 5 2^(nd) cycle 2 100 wt % water Yes, argon 13 0 2 3 99 wt % water + no >>100 >50 after 5 1 wt % vitamin C 2^(nd) cycle 4 99 wt % water + Yes, argon 5 0 0 1 wt % vitamin C

Discussion of Results

Example 1 and 2 show the influence of atmosphere replacement in the packaging by the inert gas argon. After the sterilization in air (Example 1) the wetted hydrophilic coating performance has deteriorated completely. After replacement of the air with argon (Example 2) the lubricity increased slightly (˜3-8 grams) from an unsterilized case while the durability remained similar to the unsterilized case.

Example 3 and 4 show the additional benefit of a radical and oxygen scavenger in the wetting agent. Without atmosphere replacement with argon (Example 3), a complete deterioration of wetted hydrophilic coating was observed despite the presence of vitamin C. The presence of vitamin C further improved the wetted hydrophilic coating performance after atmosphere replacement with argon (Example 4), such that no deterioration is observed.

All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. While certain embodiments detail certain optional features as further embodiments of the invention, the description is meant to encompass and specifically disclose all combinations of these features unless specifically indicated otherwise or physically impossible. 

1. A method of reducing the deterioration of a wetted hydrophilic coating comprising water at the time of sterilization by radiation comprising the step of reducing the amount of oxygen in an atmosphere in contact with the wetted hydrophilic coating in addition to any reduction in oxygen provided by oxygen scavengers that may be present in the wetted hydrophilic coating, wherein the wetted hydrophilic coating comprises at least 70 wt % water, based on the total weight of the wetted hydrophilic coating.
 2. The method of claim 1, wherein the wetted hydrophilic coating is formed by bringing a wetting agent into contact with a hydrophilic coating, and wherein the hydrophilic coating is formed by curing a hydrophilic coating composition, the hydrophilic coating composition comprising at least 70 wt % of hydrophilic polymers, based on the total dry weight of the hydrophilic coating composition.
 3. The method of claim 1 wherein the amount of oxygen in the atmosphere in contact with the wetted hydrophilic coating is reduced below 15% by volume of the atmosphere in contact with the wetted hydrophilic coating.
 4. The method of claim 1 wherein the step of reducing the amount of oxygen in the atmosphere in contact with the wetted hydrophilic coating comprises replacing at least some of the oxygen in the atmosphere in contact with the wetted hydrophilic coating with an alternative gas.
 5. The method of claim 1 further comprising the step of incorporating a radical scavenger in the wetted hydrophilic coating.
 6. The method of claim 5 wherein the step of incorporating a radical scavenger in the wetted hydrophilic coating is performed by wetting a hydrophilic coating with a wetting agent comprising the radical scavenger.
 7. The method of claim 1 further comprising the step of enclosing an article comprising the wetted hydrophilic coating in a gas impermeable packaging.
 8. The method of claim 7 wherein the step of reducing the amount of oxygen in the atmosphere in contact with the wetted hydrophilic coating comprises incorporating an oxygen scavenging packaging component inside the gas impermeable packaging or as part of the gas impermeable packaging itself.
 9. The method of claim 1 further comprising the step of sterilizing an article comprising the wetted hydrophilic coating with radiation by gamma rays or electron beam.
 10. The method of claim 1 wherein the wetted hydrophilic coating is wetted by a wetting agent comprising from 1 wt % to 20 wt % of a component selected from the group consisting of glycerol, monoacetin, diacetin, diacetone alcohol, diethyleneglycol, triethyleneglycol, tetraethyleneglycol, propyleneglycol and dipropyleneglycol.
 11. A method of sterilizing a packaged article comprising the step of sterilizing with radiation a package comprising an article and a gas impermeable packaging enclosing the article, the article comprising a wetted hydrophilic coating, the wetted hydrophilic coating comprising water, and the package comprising an amount of oxygen that is less than an amount of oxygen that would have been present in the package if oxygen scavengers that may be present in the wetted hydrophilic coating were alone acting on ambient air at the time of packaging within the gas impermeable packaging, wherein the wetted hydrophilic coating comprises at least 70 wt % water, based on the total weight of the wetted hydrophilic coating.
 12. (canceled)
 13. (canceled)
 14. A package comprising a. an article comprising a wetted hydrophilic coating, the wetted hydrophilic coating comprising water, wherein the wetted hydrophilic coating comprises at least 70 wt % water, based on the total weight of the wetted hydrophilic coating, b. a gas impermeable packaging enclosing the article, and c. an atmosphere within the gas impermeable packaging and in contact with the wetted hydrophilic coating that has an amount of oxygen that is less than an amount of oxygen that would have been present if oxygen scavengers that may be present in the wetted hydrophilic coating were alone acting on ambient air at the time of packaging within the gas impermeable packaging.
 15. The package of claim 14, wherein the wetted hydrophilic coating further comprises a radical scavenger.
 16. The package of claim 14, wherein the wetted hydrophilic coating comprises at least 90 wt % water.
 17. The package of claim 15, wherein the wetted hydrophilic coating comprises at least 90 wt % water.
 18. The method of claim 2 wherein the step of reducing the amount of oxygen in the atmosphere in contact with the wetted hydrophilic coating comprises replacing at least some of the oxygen in the atmosphere in contact with the wetted hydrophilic coating with an alternative gas.
 19. The method of claim 18 further comprising the step of incorporating a radical scavenger in the wetted hydrophilic coating.
 20. The method of claim 5, wherein the radical scavenger is vitamin C or a compound comprising a thiosulfate anion.
 21. The method of claim 19, wherein the radical scavenger is vitamin C or a compound comprising a thiosulfate anion.
 22. The method of claim 21 further comprising the step of enclosing an article comprising the wetted hydrophilic coating in a gas impermeable packaging. 